1. Field of the Invention
This invention relates in general to a semiconductor device. More specifically, the present invention relates to function selection circuit by way of fuse option manner.
2. Description of Related Art
A memory, as a semiconductor device, comprises different bit configuration on the same chip, such as ×4 bit, ×8 bit, ×16 bit, etc. The semiconductor device generally further comprises configurations corresponding to a plurality of different external power source voltages, such as 5V, 3.3V, 1.8V, etc. Conventionally, switching of the configurations is implemented by altering wiring patterns at wiring layers. However, when switching the configuration is performed by altering wiring patterns, the productivity of the semiconductor device is decreased since the wiring patterns have to be altered during the wafer manufacturing process.
In order to increase the productivity, a bonding option scheme and a fuse option scheme are used. The bonding option scheme performs the switching of the function configurations by applying the power source voltage or the ground voltage to a particular bonding pad. In addition, the fuse option scheme performs the switching of the function configurations by cutting particular fuses. Japanese Patent No. 2943784 discloses the aforementioned methods.
In particular, the bonding option scheme can carry out a product selection at a chip assembling process subsequent to the wafer manufacturing process. Therefore, the productivity is increased in comparison with the method in which the wiring patterns are altered during the wafer manufacturing process.
However, when the bonding option scheme is used, a plurality of bonding pads for switching the bit configurations is required. A reduction in the area of the semiconductor chip is achieved due to the size reduction, but the size of the bonding pads formed in the semiconductor chip is determined by the restriction of the assembly device, etc., the size of the bonding pads cannot be reduced. Therefore, if the bonding option scheme is used, there might be a problem that the entire area of the semiconductor chip will increase due to the area occupied by the bonding pads.
On the other hand, the fuse option scheme can suppress an increase in the chip area, which is an issue for the boding option scheme. However, in contrast to that the bonding fuse scheme can perform the production selection at the assembling process, the fuse option scheme has to perform the production selection at a probing process that is implemented before the assembling process. For the fuse option scheme, in most cases, the chip cannot be changed to other functions once the fuse is cut off. Therefore, for the fuse option scheme, if compared with the method that the wiring patterns are changed at the wafer manufacturing process, the productivity is increased since the production selection is performed at the probing process subsequent to the wafer manufacturing process. However, the productivity is worse in comparison with the bonding fuse scheme where the production selection is performed at the assembling process subsequent to the probing process.